The use of sacrificial anodes for protecting steel, brass, bronze or aluminum parts from corrosion in sea water is well established in marine engineering. It is thus well known that, for example, steel propeller shafts with bronze bearings are subject to corrosive electrochemical galvanic reaction in sea water that shortens the potential lifetime of the shaft. To protect the shaft from corrosion, a replaceable sacrificial anode is placed near the shaft. The anode is typically made of a metal (most often zinc) that is subject to preferential corrosion relative to the shaft material when the parts are submerged in an electrolyte such as sea water. In such a case, it is desirable to mount the sacrificial anode in a way the permits the anode to be replaced without having to detach the propeller.
A similar propeller design is described in U.S. Pat. No. 4,077,742 in which a nose piece, or so called spinner, apart from its hydrodynamic drag-reducing function, also serves as a sacrificial zinc anode mounted on a reusable brass propeller fastener nut. A problem with this design is, however, that the original outer peripheral contour of the spinner that is shaped for optimum hydrodynamic performance-gradually deteriorates and roughens as corrosion of the anodic material in the spinner proceeds, causing increased drag and loss of propulsion performance.